Southwest faces even hotter, drier conditions

FLAGSTAFF, Ariz. (AP) — Hotter, drier conditions in the already drought-stricken Southwest are expected to further stress the region's water supply, threatening specialty crops and making forests more vulnerable to wildfires and tree-killing insects.

The Obama administration released the National Climate Assessment on Tuesday. Among the highlights in the Southwestern U.S., which include California, Nevada, Arizona, Utah, Colorado and New Mexico, are:

— AGRICULTURE: Artichokes, olives and apricots might not be as visually pleasing as drought and extreme weather continue to take a toll on the crops grown primarily in California. A combination of longer frost-free seasons, less frequent blasts of cold air and more heat waves is projected to intensify, leading to faster ripening. The report says farmers might not be able to adapt quickly enough. Trees that bear nuts and fruit that need winter chills will have lower yields. Vegetables grown in the warmer seasons might not be viable under hotter conditions.

— WATER SUPPLY: Southwestern cities know they must conserve water, but the report says that alone won't be enough to meet demand. Drier winters and early snowmelts are threatening the region's water supplies. The flow of water in the Sacramento-San Joaquin River Delta, the Colorado and Rio Grande rivers and the Great Basin were 5 percent to 37 percent lower between 2001 and 2010 than average flows in the 20th century. As water utilities across the Southwest try to prepare for the effects of climate change, key strategies for boosting supply will include expanding the treatment of wastewater and desalination.

— WILDFIRES AND BARK BEETLES: The number of acres scorched by wildfires could double in the southern Rockies and increase by 74 percent in California due to climate change, driving up firefighting costs, threatening public health and damaging homes and the economy. The report highlights the 2003 Grand Prix Fire in Southern California, which caused $1.2 billion in damage. Drought and warmer temperatures also prompt outbreaks of bark beetles, making the landscape even more vulnerable. From 1984 to 2008, wildfires and bark beetles have combined to kill trees across 20 percent of Arizona and New Mexico forests.

— HEAT WAVES: More than 90 percent of people living in the Southwest make their homes in cities, a figure higher than in any other region in the U.S. Rising temperatures leave people struggling to keep cool, resulting in skyrocketing demand for electricity and widespread power outages. California, Nevada, Utah, New Mexico, Colorado and Arizona have seen some their warmest summer months on record in recent years. Consecutive days of scorching heat also can be deadly, particularly among the elderly and people illegally crossing the border from Mexico. The nation's highest rates of heat-related deaths are in Arizona.